Asymmetric encryption method developed in 1984. It is used in PGP implementations and GNU Privacy Guard Software. Consists of 3 parts: key generator, encryption algorithm, and decryption algorithm.
Correct Answer: D
ElGamal https://en.wikipedia.org/wiki/ElGamal_encryption the ElGamal encryption system is an asymmetric key encryption algorithm for public-key cryptography which is based on the Diffie-Hellman key exchange. It was described by Taher Elgamal in 1985. ElGamal encryption is used in the free GNU Privacy Guard software, recent versions of PGP, and other cryptosystems. The Digital Signature Algorithm (DSA) is a variant of the ElGamal signature scheme, which should not be confused with ElGamal encryption. Incorrect answers: Tiger - is a cryptographic hash function designed by Ross Anderson and Eli Biham in 1995 for efficiency on 64-bit platforms. The size of a Tiger hash value is 192 bits. Truncated versions (known as Tiger/128 and Tiger/160) can be used for compatibility with protocols assuming a particular hash size. Unlike the SHA-2 family, no distinguishing initialization values are defined; they are simply prefixes of the full Tiger/192 hash value. GOST - hash function, defined in the standards GOST R 34.11-94 and GOST 34.311-95 is a 256-bit cryptographic hash function. It was initially defined in the Russian national standard GOST R 34.11-94 Information Technology - Cryptographic Information Security - Hash Function. The equivalent standard used by other member-states of the CIS is GOST 34.311-95. RIPEMD - is a family of cryptographic hash functions developed in 1992 (the original RIPEMD) and 1996 (other variants). There are five functions in the family: RIPEMD, RIPEMD-128, RIPEMD-160, RIPEMD-256, and RIPEMD-320, of which RIPEMD-160 is the most common.
Question 52
Hash algortihm created by the Russians. Produces a fixed length output of 256bits. Input message is broken up into 256 bit blocks. If block is less than 256 bits then it is padded with 0s.
Correct Answer: B
GOST https://en.wikipedia.org/wiki/GOST_(hash_function) The GOST hash function, defined in the standards GOST R 34.11-94 and GOST 34.311-95 is a 256-bit cryptographic hash function. It was initially defined in the Russian national standard GOST R 34.11-94 Information Technology - Cryptographic Information Security - Hash Function. The equivalent standard used by other member-states of the CIS is GOST 34.311-95. Incorrect answers: BEAR - BEAR block cipher was invented by Ross Anderson and Eli Biham by combining a stream cipher and a cryptographic hash function. TIGER - is a cryptographic hash function designed by Ross Anderson and Eli Biham in 1995 for efficiency on 64-bit platforms. The size of a Tiger hash value is 192 bits. Truncated versions (known as Tiger/128 and Tiger/160) can be used for compatibility with protocols assuming a particular hash size. Unlike the SHA-2 family, no distinguishing initialization values are defined; they are simply prefixes of the full Tiger/192 hash value. FORK-256 - is a hash algorithm designed in response to security issues discovered in the earlier SHA-1 and MD5 algorithms. After substantial cryptanalysis, the algorithm is considered broken.
Question 53
A transposition cipher invented 1918 by Fritz Nebel, used a 36 letter alphabet and a modified Polybius square with a single columnar transposition.
Correct Answer: A
ADFVGX Cipher https://en.wikipedia.org/wiki/ADFGVX_cipher ADFGVX cipher was a field cipher used by the German Army on the Western Front during World War I. ADFGVX was in fact an extension of an earlier cipher called ADFGX. Invented by Lieutenant Fritz Nebel (1891-1977) and introduced in March 1918, the cipher was a fractionating transposition cipher which combined a modified Polybius square with a single columnar transposition. Incorrect answers: Book Ciphers - or Ottendorf cipher, is a cipher in which the key is some aspect of a book or other piece of text. Books, being common and widely available in modern times, are more convenient for this use than objects made specifically for cryptographic purposes. It is typically essential that both correspondents not only have the same book, but the same edition. Cipher Disk - enciphering and deciphering tool developed in 1470 by the Italian architect and author Leon Battista Alberti. He constructed a device, (eponymously called the Alberti cipher disk) consisting of two concentric circular plates mounted one on top of the other. The larger plate is called the "stationary" and the smaller one the "moveable" since the smaller one could move on top of the "stationary" ROT13 Cipher - simple letter substitution cipher that replaces a letter with the 13th letter after it, in the alphabet. ROT13 is a special case of the Caesar cipher which was developed in ancient Rome.
Question 54
_____ uses at least two different shifts, changing the shift with different letters in the plain text.
Correct Answer: B
multi-alphabet encryption https://en.wikipedia.org/wiki/Polyalphabetic_cipher Two different shifts create two different alphabets. For +1 and +2 Plaintext alphabet A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 2 ciphertext alphabets B C D E F G H I J K L M N O P Q R S T U V W X Y Z A C D E F G H I J K L M N O P Q R S T U V W X Y Z A B Incorrect answers: Scytale - transposition cipher Caesar cipher - monoalphabetic cipher Atbash - monoalphabetic cipher
Question 55
What is the largest key size that AES can use?
Correct Answer: A
256 https://en.wikipedia.org/wiki/Advanced_Encryption_Standard For AES, NIST selected three members of the Rijndael family, each with a block size of 128 bits, but three different key lengths: 128, 192 and 256 bits.
